Hi stranger! Signing up for MypetMD is easy, free and puts the most relevant content at your fingertips.

Get Instant Access To

  • 24/7 alerts for pet-related recalls

  • Your own library of articles, blogs, and favorite pet names

  • Tools designed to keep your pets happy and healthy



or Connect with Facebook

By joining petMD, you agree to the Privacy Policy.

petMD Blogs

Written by leading veterinarians to provide you with the information you need to care for your pets.

The Daily Vet by petMD

The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.

Isoflavones May Reduce Body Fat in Dogs

The isoflavones and isoflavonoids found in soybeans have long been known to have antioxidant properties that decrease the tissue damage of normal cell metabolism. It is also known that human populations that consume foods high in these organic compounds have lower incidences of breast cancer and other common cancers. Now veterinary scientists have found that isoflavones fed to dogs increases daily energy expenditure and reduces body fat accumulation without a reduction in calorie intake.

What are Isoflavones?

Isoflavones are found naturally in soybeans. Green beans, alfalfa sprouts, mung bean sprouts, cowpeas, kudzu root and red clover also contain these organic chemicals. Even highly processed foods like tofu retain isoflavones and the fermenting of miso (a soy derived paste used in Chinese and Japanese dishes) actually increases isoflavones. Isoflavones help protect their parent plant from fungal and bacterial diseases. The isoflavones in soybeans also stimulate soil organism to form the nitrogen absorbing root nodules that promote the protein storing capacity of these food sources.

Cancer prevention is believed to result from the estrogen-like properties of isoflavones that interferes with breast cancer cell growth. This hormonal influence is also though to interfere with the metabolism and biological activity of other types of cancer cells. These cancer protecting properties of isoflavones are believed to be the reason that the incidence of breast cancer is much lower in human cultures where soybeans and mung beans are a large part of the normal diet. It is this estrogen hormone activity that may also influence pet obesity.

Isoflavones and Fat in Dogs

Veterinary researchers studied two groups of spayed/neutered Labrador Retrievers, a dog breed notorious for having tendencies toward obesity after sexual alteration (i.e., neutering/spaying). The diet for both groups was identical in protein, fat, carbohydrate and calorie content. The only difference was that one diet contained isoflavones and the other contained none. The dogs were fed 25 percent more than their calculated daily energy requirement for nine months, as they were being monitored for their energy or calorie expenditure and percentage of body fat. The isofalvone group had significantly greater energy expenditure and reduced body fat accumulation at the end of the nine month period. The researchers attributed the results to the estrogen-like activity of the isoflavones.

The elimination or reduction of sex hormones in spayed or neutered dogs is known to significantly reduce energy expenditure in pets. This study suggests that the supplementation of natural estrogen compounds like isoflavones reverses this energy metabolism decline and may prevent obesity in sexually altered pets.

Soy Products and Dog Food

The findings in this study are compelling for the addition of soy products to commercial pet food. Unfortunately soy is not likely to become commonplace in pet food in the near future.

Although soy protein is found in some premium pet foods, it is not a common ingredient in most commercial dog foods. The obvious reason for this is cost. Soybeans and soybean products are a large part of the diet for many countries and cultures that are unable to produce an adequate supply for their own population. Soy containing products are also popular in the U.S. and other Western countries despite not being a staple of the normal western diet. This worldwide demand for U.S. produced soybeans increases the price. Commercial pet food is extremely price sensitive. To maintain target price points and consumer loyalty, commercial pet food companies must substitute less expensive sources of protein.

The bright side, however, is that the study was funded by a major pet food company, which suggests that they will be rolling out a product with significant soy or isoflavone content. I am pursuing contact with them and the researchers and I will keep you posted. In the meantime, consult your veterinarian about how you might incorporate soybeans, tofu or miso into your dog’s diet.

Dr. Ken Tudor

Image: vegetarian by 8 Kome / via Flickr


Meet The Vets